1. Field of the Invention
This invention relates to a process for producing a dye-containing negative curable composition suitable for forming a colored image constituting a color filter to be used for a liquid crystal display device (LCD), a solid state image pickup device (CCD, CMOS, etc.) or the like, a color filter produced by using the dye-containing negative curable composition produced by the production process, and a production process for the color filter.
2. Description of the Related Art
As processes for producing a color filter used for liquid crystal display devices and solid state image pickup devices, a staining process, a printing process, an electrodeposition process and a pigment dispersion process are known.
In a pigment dispersion process, a color filter is produced by a photolithographic process using a colored radiation-sensitive composition prepared by dispersing a pigment in a photosensitive composition. Color filters produced by this process are stable with respect to light, heat and the like since pigments are used. A high positional accuracy can be obtained in this process since patterning is carried by a photolithographic process, and this process has been widely used as a process suitable for preparing a color filter for a large-screen and high-resolution color display.
In producing a color filter by a pigment dispersion process, a radiation-sensitive composition is first coated on a glass substrate with a spin coater or a roll coater and dried to form a coated film. Then, colored picture elements are formed by pattern exposure and development of the coated film. A color filter can be produced by performing this operation for each color.
It has been disclosed that a negative photosensitive composition in which a photopolymerizable monomer and a photopolymerization initiator are included together with an alkali soluble resin is used in the pigment dispersion process (e.g., see Japanese Patent Application Laid-Open (JP-A) Nos. 2-181704, 2-199403, 5-273411, 7-140654, and 54-63903).
Recently, in color filters for solid state image pickup devices, even higher resolution is desired. However, the conventional pigment dispersion processes have difficulties in further improving the resolution, and there are problems such as generation of color irregularities due to coarse particles of the pigment, and thus they are not suitable for a use which requires fine patterns such as solid state image pickup devices.
In view of the above-described problems, technologies for using dyes in place of pigments have heretofore been proposed (see JP-A No. 6-75375, for example). However, it is necessary to add a large amount of dye to a dye-containing curable composition to be used for manufacturing color filters for solid state image pickup devices due to the requirement of a film thickness of 1.0 μm or less, and coating uniformity of the dye-containing curable composition has been insufficient.
Since a colored pattern has become increasingly minute and a film thickness of the colored pattern has become increasingly thin to be used for solid state image pickup devices, contamination with minute foreign contaminants has become an issue, and establishment of a production process for achieving smoothness and uniform thickness has become remarkably important. However, now that the colored pattern has become further minute, it is difficult in the conventional technologies to obtain a dye-containing negative curable composition in which generation of and contamination with minute contaminates are suppressed, and which provides a good film thickness uniformity (in-plane uniformity) when a film is formed by coating the composition.